Avast Firewall block VPN

I am using

– Avast version 17.4.2294
– Windows 8.1

I was using VPN everything was working fine but suddenly I am not able to connect if Avast firewall is on.
If I disable Avast firewall I am able to connect with VPN.

I don’t feel confortable to leave firewall off.
Any idea?

Sure, set the correct exclusion/rule(s) for the VPN in the firewall.

https://www.avast.com/faq.php?article=AVKB25